Dyeing fabric containing cellulosic fibers is an important chemical industrial process that results in commercial textile products. The natural fibers such as wool and silk, which are cationic polyamide (protein) fibers, are typically dyed using water-soluble acid dyes containing anionic groups such as residues of sulfuric, carboxylic, or phosphoric acids. Hydrophilic cellulosic fibers such as cotton, flax, and linen contain hydroxyl groups (—OH) and can be dyed using water-soluble dyes, such as direct (substantive) dyes or reactive dyes. Direct dyes physically bond to the hydrophilic fiber, e.g., by forming hydrogen bonds with the —OH groups of the cellulosic substrate. Reactive dyes chemically react with the fiber, e.g., by forming covalent bonds with the —OH groups of the cellulose. In some instances, reactive dyes can also be applied to protein fibers such as wool and silk and to some synthetic polyamides such as nylon. Acrylic fibers (made, e.g., from acrylonitrile) may be dyed using basic dyes. Hydrophobic synthetic fibers, such as polyester and acetate fibers, are typically dyed with disperse dyes that are sparingly water-soluble and do not have reactive or ionizable groups in their structure.